Methylations catalyst charge

The unit has virtually the same flow sheet (see Fig. 2) as that of methanol carbonylation to acetic acid (qv). Any water present in the methyl acetate feed is destroyed by recycle anhydride. Water impairs the catalyst. Carbonylation occurs in a sparged reactor, fitted with baffles to diminish entrainment of the catalyst-rich Hquid. Carbon monoxide is introduced at about 15—18 MPa from centrifugal, multistage compressors. Gaseous dimethyl ether from the reactor is recycled with the CO and occasional injections of methyl iodide and methyl acetate may be introduced. Near the end of the life of a catalyst charge, additional rhodium chloride, with or without a ligand, can be put into the system to increase anhydride production based on net noble metal introduced. The reaction is exothermic, thus no heat need be added and surplus heat can be recovered as low pressure steam. 

Polar-substituted alkenes where the functionality is not attached to a strained ring are considerably more discriminating in their compatibility with metathesis catalysts and as a rule require relatively high catalyst charges. In the aliphatic series, unsaturated esters have received the most attention. Boelhouwer reported in 1972 the metathesis of the ester methyl oleate and its trans isomer, methyl elaidate, with a homogeneous catalyst based on a 1/1.4 molar combination of WCl6/(CH3)4Sn (23). At 70°C and an ester/W molar ratio of 33, near-thermodynamic equilibrium was attained, and 49 and 52% of the respective esters were converted to equal amounts of 9-octadecene and the dimethyl ester of 9-octadecene-1,18-dioic acid. 

Figure 12. Rate of methylation initial (0) versus delayed (X) catalyst charge.

Methyl linoleate is to be converted to methyl oleate in a 2-m slurry reactor. The molar feed rate of methyl linoleate to the reactor is 0.7 kmol/min. The partial pressure of H2 is 6 atm and the reactor is considered to be well-mixed. Calculate the catalyst charge necessary to achieve 30% conversion for a 60-fxm particle size. The reaction conditions are the same as those described in Example 12-5. 

Small quantities of methyl propionate and ethyl propionate present in these fractions. Liquid yield (wt %) calculated basis total catalyst charge. 

Example 86 A 0.10 mole amount of the starting 3-(4-hydroxyphenyl) propylene, 0.25 mole of methyl nitrite, 0.5 liter of methyl alcohol, and 0.006 mole of a palladium chloride catalyst were charged into a reaction vessel. Then, the reaction was carried out at a temperature of 20.degree. C. for 1.5hours."... 

Step 1 CP2Z1CI2 is converted to the active catalyst by reaction with the promoter methylalumoxane (MAO). A methyl group from MAO displaces one of the chlorine ligands of Cp2ZrCl2. The second chlorine is lost as chloride by ionization, giving a positively charged metallocene. 

VI. Uses. During the latter part of the nineteenth century and the early part of the present century, PA was widely used as the main expl charge of projectiles and bombs. This is no longer true, Indeed PA per se is hardly used as an expl. Its current limited expl-related use is primarily in the preparation of Explosive D (Ammonium Picrate) and Lead Picrate. It also finds some use as an intermediate in the manuf of dyes. There is some patent literature on the use of PA as a catalyst for polymerizations. For example, PA is claimed as catalyst in polybutadiene polymerizations (Ref 40), and for the prepn of an isobutylene-5-methyl-1,3,6 hepta-trieie copolymer (Ref 38)... 

The [Rh(CO)2I2] ion is clearly an important species in systems derived from several different catalyst precursors fortuitously, it is a relatively nucleophilic rhodium species. Thus it reacts with methyl iodide at room temperature, whereas the related uncharged species, [Rh(CO)2Cl]2, is unreactive toward methyl iodide at low temperatures. This difference between neutral and charged species is also evidenced markedly in the relative reactivities of [RhL2(CO)X] and [RhL(CO)X2] toward methyl iodide, where a difference of five orders of magnitude has been observed (19). 

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